I am wondering if there is some objetive technique to solve this sudoku attached. I already tried X-WING, XY-WING, SWORDFISH and others like that but it looks like nothing works out.

I know at this stage of the puzzle I could "guess" some numbers and try finding the remaining options, checking if it matches or getting to an "impossible solution" (in this case I would discard such guess).

A (partially) good observation, and a small wonder no one else mentioned that. With the presented board that's clearly the simplest solution. However, would you agree that some solved cells in the board don't make much sense even though they're all technically correct? Specifically, how were 5r2c5 and 9r2c8 solved? I don't see any obvious way to do that at this stage (except nets, but such complexity makes little sense here). I bet the other replies were based only on the givens, and the two mysteriously solved cells and the resulting naked pair went unnoticed (because they would not appear in a normal solve path).